Named the Greatest Briton of all time in a 2002 poll, Sir Winston Leonard Spencer - Churchill (丘吉尔）, the Prime Minister of the United Kingdom from 1940 to 1945 and again from 1951 to 1955, is widely regarded as being among the most influential people in British history.
Lady Astor (Nancy Astor, Viscountess Astor) was the first female Member of Parliament to take her seat. She is nearly as famous for her scathing wit as she is for her political career. "Women have got to make the world safe for men since men have made it so darned unsafe for women."
On the postcard, Lady Astor said to Churchill, if she was his wife, she would poison his coffee, to which he responded, if she was his wife, he would drink it. (I'd rather die were you my wife.)